U.S. NAVY SALVAGE REPORT DEEPWATER HORIZON ... - ESSM

Deepwater Horizon Oil Spill Response
2 to 3 knot current. On 19 May SUPSALV received reports that the strong current was impacting
the boom and resulting in failures at the boom end attachment points and that anchors were
dragging. Responding to these issues, SUPSALV requested GPC’s Mr. Bob Urban, one of the
designers of SUPSALV boom, to provide guidelines on Navy boom strength and oil entrainment
characteristics. These guidelines were issued on 20 May. They indicated that the safe working
load for the boom assembly is 20,000 lbs and that 1000 foot lengths of boom across the Mobile
Bay entrance (with peak currents of 2.8 kts) would result in 66,000 lbs of tensile load.
Additionally, booms were limited in their capacity to contain oil in currents above 0.8 knots.
SUPSALV distributed this guidance and requested the Mobile Bay Task Leaders to adjust their
booming plan accordingly. A copy of this guidance is provided in Appendix A. Within days of
this incident, regional and USCG task leaders were indoctrinated in correct booming strategy in
high current areas. Their follow-on plans reflected oil deflection strategy with boom nearly
aligned with the current funneling oil to standby skimmers as opposed to blocking strategy.
Figure 5-16. Mobile Bay Ship Channel initial oil containment boom
deployment plan that lead to boom failure.
Mooring Systems - Initially, with Ship Island providing the first data point, it appeared that the
number of mooring systems available in the ESSM inventory would be insufficient to deploy all of
the containment boom brought to the Gulf. The concept of cascading boom required two
mooring sets per 1000 feet of boom. With this strategy, the inventory was about 55 sets short
(worst case scenario). Since SUPSALV ordered deployment of all of the prepackaged mooring
sets, they began looking locally to identify anchors and mooring chain to supplement the ESSM
gear. The forward deployed team set on the task of obtaining additional anchors and mooring
chain suitable to the task from the local maritime economy. A significant number of mooring sets
were obtained but the booming strategy evolved over the course of the operation and the crews
5-19